[WIP] Conflict resolution - Add change history for ssh keys

docs/db_repository_update.md

@@ -0,0 +1,49 @@
+# DB Repository Update Instructions
+
+To fully implement the SSH key change history feature, the database schema needs to be updated in the [ssh-sync-db](https://github.com/therealpaulgg/ssh-sync-db) repository.
+
+## Changes Required
+
+Add the following SQL to the `init.sql` file in the ssh-sync-db repository:
+
+```sql
+-- Create enum type for change types
+CREATE TYPE change_type AS ENUM ('created', 'updated', 'deleted');
+
+-- Create table for tracking SSH key changes
+CREATE TABLE IF NOT EXISTS ssh_key_changes (
+    id UUID DEFAULT uuid_generate_v4() NOT NULL,
+    ssh_key_id UUID NOT NULL,
+    user_id UUID NOT NULL,
+    change_type change_type NOT NULL,
+    filename VARCHAR(255) NOT NULL,
+    previous_data BYTEA,
+    new_data BYTEA,
+    change_time TIMESTAMP WITH TIME ZONE NOT NULL,
+    PRIMARY KEY (id),
+    FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
+);
+
+-- Add indexes for efficient lookups
+CREATE INDEX IF NOT EXISTS idx_ssh_key_changes_ssh_key_id ON ssh_key_changes(ssh_key_id);
+CREATE INDEX IF NOT EXISTS idx_ssh_key_changes_user_id ON ssh_key_changes(user_id);
+CREATE INDEX IF NOT EXISTS idx_ssh_key_changes_change_time ON ssh_key_changes(change_time);
+
+-- Add index for the most common query pattern: finding the latest changes per key for a user
+CREATE INDEX IF NOT EXISTS idx_ssh_key_changes_user_time ON ssh_key_changes(user_id, change_time DESC);
+```
+
+## Implementation Notes
+
+1. The schema matches what's defined in the `docs/sql/ssh_key_changes.sql` file in this repository
+2. The schema uses the existing `uuid_generate_v4()` function that's already being used in the database
+3. The table includes a foreign key reference to the users table with cascade deletion to ensure data integrity
+4. Indexes have been added to optimize the most common query patterns
+
+## Testing
+
+After updating the init.sql file in the ssh-sync-db repository, you can test that the schema works correctly by:
+
+1. Running `docker-compose up --build` in the ssh-sync-db repository
+2. Connecting to the database with `psql -h localhost -p 5432 -U sshsync -d sshsync`
+3. Verifying the table exists with `\d ssh_key_changes`

docs/sql/ssh_key_changes.sql

@@ -0,0 +1,25 @@
+-- Schema for SSH Key Change tracking
+
+-- Create enum type for change types
+CREATE TYPE change_type AS ENUM ('created', 'updated', 'deleted');
+
+-- Create table for tracking SSH key changes
+CREATE TABLE IF NOT EXISTS ssh_key_changes (
+    id UUID PRIMARY KEY,
+    ssh_key_id UUID NOT NULL,
+    user_id UUID NOT NULL,
+    change_type change_type NOT NULL,
+    filename VARCHAR(255) NOT NULL,
+    previous_data BYTEA,
+    new_data BYTEA,
+    change_time TIMESTAMP WITH TIME ZONE NOT NULL,
+    FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
+);
+
+-- Add indexes for efficient lookups
+CREATE INDEX IF NOT EXISTS idx_ssh_key_changes_ssh_key_id ON ssh_key_changes(ssh_key_id);
+CREATE INDEX IF NOT EXISTS idx_ssh_key_changes_user_id ON ssh_key_changes(user_id);
+CREATE INDEX IF NOT EXISTS idx_ssh_key_changes_change_time ON ssh_key_changes(change_time);
+
+-- Add index for the most common query pattern: finding the latest changes per key for a user
+CREATE INDEX IF NOT EXISTS idx_ssh_key_changes_user_time ON ssh_key_changes(user_id, change_time DESC);

docs/ssh_key_change_history.md

@@ -0,0 +1,36 @@
+# SSH Key Change History
+
+This feature adds support for tracking changes to SSH keys in the database, allowing for better conflict resolution during syncing.
+
+## Database Schema
+
+The feature introduces a new table `ssh_key_changes` that tracks all changes (creation, updates, and deletions) to SSH keys. 
+See the SQL schema in `docs/sql/ssh_key_changes.sql`.
+
+**Note**: This schema needs to be added to the init.sql file in the separate [ssh-sync-db](https://github.com/therealpaulgg/ssh-sync-db) repository. See `docs/db_repository_update.md` for detailed instructions.
+
+## API Usage
+
+### Recording Changes
+
+Changes are automatically recorded when using the new repository methods:
+
+- `SshKeyRepo.CreateSshKeyWithChange`: Create a new SSH key and record it as a creation event
+- `SshKeyRepo.UpsertSshKeyWithChange`: Create or update an SSH key and record the appropriate event
+- `SshKeyRepo.UpsertSshKeyWithChangeTx`: Same as above but within a transaction
+- `UserRepo.DeleteUserKeyTx`: Now records a deletion event before deleting the key
+
+### Retrieving Change History
+
+Use the `SshKeyChangeRepository` to access change history:
+
+- `GetKeyChanges`: Retrieve the full change history for a specific SSH key
+- `GetLatestKeyChangesForUser`: Get the most recent change for each of a user's SSH keys since a specified time
+
+## Conflict Resolution
+
+This change history enables better conflict resolution during syncing:
+
+1. When a key is deleted on the server, clients can detect this change and delete it locally
+2. When both server and client have made changes to the same key, the timestamps can be used to determine which change is more recent
+3. In case of conflicts, the application can choose to keep the most recent change or prompt the user for resolution

go.mod

@@ -1,6 +1,7 @@
 module github.com/therealpaulgg/ssh-sync-server
 
-go 1.23
+go 1.23.0
+
 toolchain go1.24.1
 
 require (

internal/setup/main.go

@@ -46,6 +46,14 @@ func SetupServices(i *do.Injector) {
 		dataAccessor := do.MustInvoke[database.DataAccessor](i)
 		return &query.QueryServiceTxImpl[models.SshConfig]{DataAccessor: dataAccessor}, nil
 	})
+	do.Provide(i, func(i *do.Injector) (query.QueryService[models.SshKeyChange], error) {
+		dataAccessor := do.MustInvoke[database.DataAccessor](i)
+		return &query.QueryServiceImpl[models.SshKeyChange]{DataAccessor: dataAccessor}, nil
+	})
+	do.Provide(i, func(i *do.Injector) (query.QueryServiceTx[models.SshKeyChange], error) {
+		dataAccessor := do.MustInvoke[database.DataAccessor](i)
+		return &query.QueryServiceTxImpl[models.SshKeyChange]{DataAccessor: dataAccessor}, nil
+	})
 	do.Provide(i, func(i *do.Injector) (repository.UserRepository, error) {
 		return &repository.UserRepo{Injector: i}, nil
 	})
@@ -58,5 +66,7 @@ func SetupServices(i *do.Injector) {
 	do.Provide(i, func(i *do.Injector) (repository.SshConfigRepository, error) {
 		return &repository.SshConfigRepo{Injector: i}, nil
 	})
-
+	do.Provide(i, func(i *do.Injector) (repository.SshKeyChangeRepository, error) {
+		return &repository.SshKeyChangeRepo{Injector: i}, nil
+	})
 }

pkg/database/models/ssh_key_change.go

@@ -0,0 +1,31 @@
+package models
+
+import (
+	"time"
+
+	"github.com/google/uuid"
+)
+
+// ChangeType represents the type of change made to an SSH key
+type ChangeType string
+
+const (
+	// Created indicates a new SSH key was created
+	Created ChangeType = "created"
+	// Updated indicates an existing SSH key was updated
+	Updated ChangeType = "updated"
+	// Deleted indicates an SSH key was deleted
+	Deleted ChangeType = "deleted"
+)
+
+// SshKeyChange represents a change to an SSH key in the database
+type SshKeyChange struct {
+	ID            uuid.UUID  `json:"id" db:"id"`
+	SshKeyID      uuid.UUID  `json:"ssh_key_id" db:"ssh_key_id"`
+	UserID        uuid.UUID  `json:"user_id" db:"user_id"`
+	ChangeType    ChangeType `json:"change_type" db:"change_type"`
+	Filename      string     `json:"filename" db:"filename"`
+	PreviousData  []byte     `json:"previous_data,omitempty" db:"previous_data"`
+	NewData       []byte     `json:"new_data,omitempty" db:"new_data"`
+	ChangeTime    time.Time  `json:"change_time" db:"change_time"`
+}

pkg/database/query/transaction_mock.go

@@ -0,0 +1,36 @@
+package query
+
+import (
+	"github.com/jackc/pgx/v5"
+)
+
+// TransactionMock implements the TransactionService interface for testing
+type TransactionMock struct {
+	StartTxFunc  func(pgx.TxOptions) (pgx.Tx, error)
+	CommitFunc   func(pgx.Tx) error
+	RollbackFunc func(pgx.Tx) error
+}
+
+// StartTx implements TransactionService
+func (m *TransactionMock) StartTx(opts pgx.TxOptions) (pgx.Tx, error) {
+	if m.StartTxFunc != nil {
+		return m.StartTxFunc(opts)
+	}
+	return nil, nil
+}
+
+// Commit implements TransactionService
+func (m *TransactionMock) Commit(tx pgx.Tx) error {
+	if m.CommitFunc != nil {
+		return m.CommitFunc(tx)
+	}
+	return nil
+}
+
+// Rollback implements TransactionService
+func (m *TransactionMock) Rollback(tx pgx.Tx) error {
+	if m.RollbackFunc != nil {
+		return m.RollbackFunc(tx)
+	}
+	return nil
+}